Nonwandering hardening compounds and their use

ABSTRACT

Low molecular weight, nonwandering compounds for hardening natural and synthetic colloids without afterhardening. These comprise compounds having the structural formula: WHEREIN EACH R is hydrogen, an aliphatic or aromatic radical, and R2 and each R3 are hydrogen or lower alkyl.

I United States Patent [151 3,640,720

Cohen Feb. 8, 1972 [54] NONWANDERING HARDENING 851,339 10/1952 GermanyCOMPOUNDS AND THEIR USE 67/2333 9/1967 [72] lnventor: Hyman L. Cohen,Rochester, N.Y. Primary xaminer-J Travis Bro n Assistant Examiner-JohnWinkelman I73] Asmgnec: fisztman Kodak Company, Rochester, Anomy AnenRosenberg 22 Filed: Aug. 27, 1970 1 ABSTRACT [21 1 APPL 7 577 Lowmolecular weight, nonwandering compounds for hardening natural andsynthetic colloids without afterhardening. Related US. Application DataThese comprise compounds having the structural formula:

[63] Continuation of Ser. No. 682,530, Nov. 13, 1967. 3 0 O O R3 [52 US.or ..96/lll,260/1 17 ll l [51 int. Cl ..G03c 1/30 CH=CCNCNCC=C H 58FieldofSearch ..96/l11;260/1l7 l R R H R [56] References Cited FOREIGNPATENTS OR APPLICATIONS Great Britain ..96/1 1 1 wherein each R ishydrogen, an aliphatic or aromatic radical.

and R and each R are hydrogen or lower alkyl.

6 Claims, No Drawings NONWANDERING HARDENING COMPOUNDS AND THEIR USEThis is a continuation of application Ser. No. 682,530 filed Nov. 13,1967 by applicant.

BACKGROUND OF THE INVENTION 1. Field of the invention This inventionrelates to new and novel nonwandering compounds useful for hardeningnatural and synthetic materials, such as polymers, withoutafterhardening. In one aspect the invention relates to photographicsilver halide emulsions comprising gelatin hardened by said compounds.

2. Description of the Prior Art The use 'of a natural polymer such asgelatin, aloneand in combination with synthetic polymers as vehicles,particularly for photographic purposes, often requires treatment with asuccession of aqueous baths of variable pH or of increased temperature.Much work has already been done in treating natural synthetic polymersto improve their resistance to water so that swelling and melting do notoccur upon treatment thereof with aqueous solutions in processingoperations or in hot drying. Various compounds have previously beenfound useful for treating photographic binders containing gelatin, forexample, so as to prevent swelling or melting during processing.

Metallic salts, for instance, such as those of chromium, aluminum, andzirconium tend to react and harden gelatin so very quickly that theiraddition, before shaping, in quantities required to achieve the desiredhardening, involves the risk of premature coagulation of the gelatinsolution.

Aldehydes such as formaldehyde are partly volatilized when dryingmaterials containing them so that an accurate dosage is difficult torealize. Diketones of the l,2-, l,4- type, among which group thequinones might be considered members, tend to cause a loss of speed ofphotographic emulsion upon storage.

Many of the known hardeners act slowly so that a long period of time isnecessary to attain a sufficiently stabilized state of hardening. As aconsequence, the development properties and sensitometriccharacteristics of a photographic emulsion layer containing thesechanges in a manner which cannot be controlled. This undesirable effectis designated as afterhardening" and is particularly detrimentalbecause, as the layer continues to harden during storage, itspermeability to processing solutions decreases. This causes inadequatedevelopment and adversely affects the speed of the photographic layer.

Other hardeners exert their hardening action not only upon material inwhich they are placed but wander or migrate into adjacent hardenablematerial, e.g., adjacent photographic layers, causing unwanted orundesirable effects.

Still other hardeners require strong heating to produce a sufficientdegree of hardening. Strong heating is undesirable in the case ofphotographic silver halide gelatin emulsions and layers since it mayeasily lead to a reduction in sensitivity and formation of fog.

Certain other simple organic hardeners require a high molecular weightballast in order to render them nondiffusible which often causes adversephysical characteristics to the photographic emulsion and results in alow and ineffective ratio of active hardening groups to ballast groups.

None of these latter-cited compounds are without afterhardeningproperties. In other words, these compounds slowly continue to hardentoward their maximum degree upon incubation.

Accordingly, it is an object of this invention to provide a new class ofcompounds exhibiting excellent hardening properties.

Another object of this invention is to provide hardening compounds whichneither adversely affect the physical and photographic properties ofnatural or synthetic materials, particularly polymers, nor wander andafterharden.

Another object of the invention is to provide improved photographicelements and emulsions.

Yet another object of this invention is to provide a class of simpleorganic hardeners which do not require ballast groups in order to makethem nonwandering.

Still another object is to provide improved photographic elementscomprising a layer hardened by these new compounds.

Another object of this invention is to provide a means for hardening ahardenable material without undesirable afterhardening.

Other objects of this invention will become apparent from an examinationof the specification and claims which follow.

SUMMARY OF THE INVENTION DESCRIPTION OF THE PREFERRED EMBODIMENTS Oneembodiment of my invention relates to a new and novel class of compoundshaving the structural formula:

where each R is hydrogen, an aliphatic or aromatic radical, and R andeach R are each hydrogen or lower alkyl radical.

Another embodiment relates to a method of hardening a layer comprisinghardenable material, which comprises incorporating a hardening compoundof the above general formula into said layer.

Still another embodiment relates to a photographic element comprising asupport and a layer hardened by a compound of the above general formula.

The new and novel compounds described herein possess good hardeningproperties when contacted with hardenable materials in any form such asin solution, emulsion or layer form. Although preferably mixed with oradded to said polymers in emulsions, they are added in any othersuitable manner with similarly good results.

The compounds of this invention are of a low molecular weight generallybeing in the range of about 168 and about 400, preferably less thanabout 320. They are comprised of two aliphatic, ethylenicallyunsaturated radicals, for example, acryloyl or crotyl, linked togetherthrough an intervening carbonyl nitrogen-containing bivalent moiety suchas urea. The said radicals can be further substituted as shown in theforegoing formula by lower alkyl groups, e.g., methyl, ethyl, propyl,butyl, and the like. This bivalent moiety can contain substituents on anitrogen atom. Suitable substituents include lower alkyl radicals, suchas, methyl, ethyl, propyl, isopropyl, butyl, and the like. Theethylenically unsaturated radicals can be unsubstituted in the alphaposition to the carbonyl group or can contain substituents such as loweralkyl, e.g., alkyl of from one to eight carbon atoms and preferablythose of one to four carbon atoms, such as, methyl, ethyl. propyl,isopropyl, butyl, and the like, or an aromatic group such as aryl andthe like, for example, a phenyl group.

The compoundsof this invention, all of which have been found to beespecially useful in the hardening of compositions of matter comprisinggelatin in accordance with my invention, can be used in any suitablehardening concentration. including, for example, concentrations of fromabout 0.5 to 10 percent based upon the weight of the hardenablematerial, e.g.,

dried gelatin, and more preferably in the range from about 0.67 to 3percent. These compounds are particularly useful in hardeningphotographic silver halide emulsions comprising gelatin, as for example,in layers. Thus, as shown by Example II, these new compounds aredecidedly good photographic hardeners, giving excellent results in bothfresh and incubated samples.

These compounds may be combined directly in the emulsion during itspreparation or, in a photographic application the already preparedemulsion may be treated during its processing by said compounds in theform of various baths and solutions such as an. acid-fixing bath.Although not readily water soluble in high concentrations, thesecompounds are useful in aqueous acid solutions in a wide range ofconcentrations.

The new compounds described in this invention can be prepared by thereaction of an unsaturated acyl isocyanate, for example, acryloylisocyanate, with an acrylamide. The presence of a free-radicalpolymerization inhibitor is desirable and useful examples arem-dinitrobenzene, pdimethylaminoanisole, and the like. These inhibitorswill not react with the isocyanate since they do not contain activehydrogen atoms and they may be used in any concentration sufficient toprevent unwanted polymerization. The compounds of this invention canalso be prepared in other ways, for example, by the reaction between ahaloacylisocyanate with an amide and the subsequent dehydrohalogenatingof the reaction product. Further, as shown by Examples IA and IB it isalso possible to prepare these new compounds according to known methodsby foregoing the step of isolating the intermediate acryloyl isocyanateprior to reaction with the acrylamide.

Suitable solvents which can be used in the aforementioned reactionsinclude I ,2-dichloroethane, chloroform, trichloroethane, and the like,but any such inert organic solvent can be satisfactorily used, providedit has a low boiling range (60-l00 C.) in order to preventpolymerization of the acrylic moieties. The use of catalysts isoptional.

.All such reactions are conducted in the presence of the desired organicsolvents at moderate temperatures and the reactions are not pressuredependent, and consequently, superatmospheric or subatmosphericpressures can be employed. As is obvious to one skilled in the art, thespecific reaction conditions, for example, temperature, pressure, andthe like depend upon the particular reactants used.

The compounds described in this application can be used effectively incombination with hardenable materials in general but they are mostadvantageously used with natural or synthetic polymers used as vehiclesor binders in preparing photographic elements. Specific materials whichcan be hardened according to the practice of this invention includehardenable materials such as polymers, for example, gelatin, colloidalalbumin, proteins, dispersed polymerized vinyl compounds, particularlythose which increase the dimensional stability of photographic materialsas exemplified by amine-containing polymers of alkyl acrylates,methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates,maleic acid, and the like.

The hardening agents described herein can be used in various kinds ofphotographic emulsions. In addition to being useful in orthochromatic,panchromatic, and infrared emulsions, they are also useful in X-ray andother nonspectrally sensitized emulsions. They can be added to theemulsions before or after the addition of any spectral sensitizing dyeswhich may be used. They are effective in sulfur and gold sensitizedsilver halide emulsions.

The materials hardened in the practice of this invention can be coatedon a wide variety of supports. Typical supports include those generallyemployed for photographic elements, as exemplified by cellulose nitratefilm, cellulose acetate film, polyvinyl acetal film, polystyrene filrn,polyethylene terephthalate film, and related films of resinous materialsas well as glass, paper, metal, wood, and the like. Supports such aspaper that are coated with a-olefin polymers, particularly polymers ofa-olefins containing two-10 carbon atoms, as for example, polyethylene,polypropylene, ethylene butene copolymers, and the like, can also beemployed.

In addition to the hardening agents disclosed herein, photographicemulsions and elements can also contain additional additives,particularly those known to be beneficial in photographic emulsions, asexemplified by spectral sensitizers, speed-increasing materials, otherhardeners, plasticizers, and the like.

The emulsions hardened by my new compounds can be used in photographicelements intended for color photography and thus may containcolor-forming couplers or used as emulsions to be developed by solutionscontaining couplers or other color-generating materials or emulsions ofthe mixed-packet type.

The silver halides employed in the photographic emulsions include any ofthe photographic silver halides as exemplified by silver bromide, silveriodide, silver chloride, silver chlorobromide, silver chloroiodide, andthe like. The silver halides used can be those which form latent imagespredominantly on the surface of the silver halide grains or those whichform latent images inside the silver halide grains.

Hardened emulsions obtained in accordance with this invention employinggelatin or other hardenable hydrophilic colloids may be used indiffusion transfer materials. In one form of this process theundeveloped silver halide is complexed in nonimage areas of the negativeto form a water-soluble compound which is permitted to diffuse to areceiving layer in which said compound precipitates out as a positivemetallic silver image. In other diffusion transfer processes, the finalimage is produced by diffusion of the developer, oxidized developer,coupler or dye, from the exposed and developed light-sensitive layer toa second layer in close proximity thereto. It is particularlyadvantageous to employ the hardeners of this invention with hardenablesubstances or in systems comprising emulsions, layers or solutions ofhardenable matter where the absence of wandering and/or afterhardeningis advantageous.

This invention can be further illustrated by the following examples ofpreferred embodiments thereof although it will be understood that theseexamples are included merely for purposes of illustration and are notintended to limit the scope of the invention unless otherwisespecifically indicated. EXAMPLE I--Preparation of N,N '-Diacryloylurea9.7 parts of acryloyl isocyanate is added to 10 parts of acrylamide and0.5 parts of m-dinitrobenzenein parts of 1,2-dichloroethane. Thismixture is refluxed under nitrogen for over 15 hours. The acryloylisocyanates are well known and previously described by Lieser and Kemnerin Ber. 84, l 195 l A small amount of solid precipitate is filtered fromthe hot resulting solution. The filtrate is cooled at about 20 C. Theresulting precipitated product is collected on a filter and dried undervacuum. The resulting crude, dry solid [(1 l parts) having an m.p. oflll-l 30 C. is tumbled with 200 parts of water for about an hour,collected on a filter and vacuum dried. This dry solid is then dissolvedin parts of boiling l,2-dichloroethane with rapid stirring. Afterfiltration and cooling, the solid product is collected on a filter anddried to yield 7 parts of final product having an m.p. of l42l44 C. A.N-Acryloyl-N'-Methacryloylurea 4.5 Parts of acrylyl chloride is addeddropwise, under nitrogen over a period of about 1 hour, to a stirred,ice-cooled suspension of 15 parts of silver cyanate and 0.2 parts ofmdinitrobenzene in 50 parts of 1,2-dichloroethane. The mixture isallowed to reach ambient temperature and stirred 15 hours.

The mixture is then centrifuged to remove suspended matter and to thesupernatant is added 4 parts of recrystallized methacrylamide and 0.2parts of m-dinitrobenzene. This mixture is heated to boiling on a steampot with stirring under nitrogen. Heating is continued for 4 hours. Thismixture is filtered hot and cooled in a freezer for about 15 hours. Theresulting solid is filtered, washed, and vacuum dried. The dry solid istumbled with 20 parts of water, filtered, and vacuum dried. The whitedry solid is recrystallized from 3 parts 1,2- dichloroethane containing002 parts dinitrobenzene yielding 0.4 parts of final product havingamelting point of l30-l 33 B. N-Methyl-N,N'-Diacryloylurea A mixture of50 parts of LLdichloroethane, parts of silver cyanate and (H parts ofn-dinitrohenzcne in ice bath under nitrogen while 4.5 parts of acrylylchloride is added dropwise over a period of 1 hour. This mixture isstirred for 15 hours at ambient temperature and is then filtered.

The filtrate is treated with 4.2 parts of N-methyl acrylamide and 0.2parts of m-dinitrobenzene and then heated 6 hours on a steam bath undernitrogen before being filtered hot. Cooling for 15 hours in a freezingcompartment gave no precipitation. The solution is evaporated to drynesson a Rinco apparatus and the resulting viscous residue cooled in afreezing unit where it partially solidifies. The precipitate is filteredand tumbled with 2.5 parts of water. The insoluble material is filteredoff and vacuum dried. it is recrystallized from hot hexane yielding 0.2parts of a light yellow solid with a melting point of 175 1 77 C.

EXAMPLE 11 As previously indicated, the compounds described herein givevery good results when used as hardening agents in photographicapplications. As illustrative of this, the compound of Example 1 isadded to bone gelatin at a concentration of l percent based on theweight of gelatin and the resulting solution coated onto a polyester[poly(ethylene terephthalate)] film support. A control sample containingno hardener is also prepared.

A sample of each film coating is tested for hardness both fresh andafter 3 days incubation at 120 F., 50 percent relative humidity, byimmersing in Kodak DK-50 developer at 25 C. for 3 minutes. The percentswell of the gelatin layer is calculated therefrom, and the resultsclearly indicate that hardening is effective, rapid, and controlled asfollows:

EXAMPLE III in order to show further the efiectiveness of thesecompounds such as that of Example I, a small amount of the No Hardener 0965 870 N,N'-diacrylnylurea l% 490 470 EXAMPLE IVN-Acryloyl-N'-mcthacryloylurea and N-mcthyl-N,N- diacryloylurea aretested as hardeners by the procedure described in Example ill exceptthat the samples are immersed in water rather than developer. Theresults are as follows:

Concentration based on weight of 5 gelatin, Percent Film coating percentswell 1 No hardener 720 N-acryloy1-N-methacryloylurea. 1' 550 D0 3 470Do 6 360 No hardener 1 590 N-methyl-N,N 1 200 Do 3 210 Do 5 100 i Inwater after 3 days incubation at 120 F. and 50% relative humidity.

EXAMPLE V As already pointed out, the compounds of this invention havesubstantially no adverse sensitometric effects on a photographicemulsion while exhibiting favorable hardening and nonwanderingcharacteristics. To illustrate, the compound of Example 1 is added toseparate portions of a photographic emulsion as described in Example 11.For comparison purposes similar samples are coated using the followinghardeners:

formaldehyde, a known hardener used in its optimum concentration;

N,N-bis(chloroacetyl)urea, disclosed in British Pat. No. 990,275(Gevaert) Apr. 28, 1965;

N-acryloyl-N'-chloroacetyl urea, hardener; and

Methylenebisacrylamide, disclosed in British Pat. No. 994,869 (Kodak),June 10, 1965.

Each of these hardening compounds is added in optimally effectivehardening concentrations, to separate portions of a photographicemulsion of the type described in Example ll. Samples of each coatingare tested for hardness as described in Example 11.

In addition, a record sample of each coating is exposed on an Eastman 1BSensitometer, processed for 5 minutes in Kodak DK-SO developer, fixed,washed and dried. These results are. reqmled follow a mixed functionPercent Percent swell coneen-- tration After 2 weeks After 2weeks basedon incubation sensitometric results incubation weight of at 120 F.,hardenablo relative Relative Relative llardonor material Fresh humidityspeed 7 Fog speed '1 Fog Control (none) 065 870 100 1.30 0.07 107 1.000.00 N,Ndiacryloylurea 1 490 470 102 0.02 0.10 118 0.07 0.12Formaldehyde 0.5 380 430 0.80 0.05 0.80 0.00 N-aeryloylN-ehloroace 3 650520 112 1.12 0.00 112 0.07 0.12 N,N-bis(ehloroaeotyl)ureu 10 390 520 1291.22 0.08 80 1.35 0.08 Methylencbisaerylarnlde 1 1,000 650 120 1.43 0.08107 0.88 0.08

hardener is added to a high-speed photographic silver EXAMPLE vbromoiodide emulsion. This is panchromatically sensitized [poly(ethyleneterephthacoverage of 340 mg. of silver and 772 hardness as in Example llwith the following results:

% Swell After 3 days Concentration Incubation at based on weight I20 F.,50% Fresh Relative humidity Film Coating of gelatin In order todemonstrate the nonwandering characteristics of the compounds of thisinvention, 6 percent by weight of N,N'- diacryloylurea is added to agelatin solution and is coated out as a layer on a cellulose acetatefilm support containing physical development nuclei. Coincidental tothis layer is placed an additional interlayer of gelatin, similarlyhardened by the above compound. These two layers on the support are thenincubated for 3 days at about 70 F. and 50 percent relative humidity.Additional layers of gelatin are added, one with silver bromoiodicle inan unhardened gelatin emulsion and, superimposed thereon, anothernonhardened protective gelatin layer. These multilayer coatings arefreshly prepared. After two weeks incubation at 120 F. and 50 percentrelative humidity, the coatings are exposed and processed in a standardsilver solvent transfer monobath by immersing the coatings for 20seconds in the monobath having a temperature of about 90 F. and thefollowing formula:

pH is adjusted to 11.0 to 11.1 with 45% KOH (7, 13-diethianonadecane-1,IQ-biS-pyridiniump-toluene-sulfonate) gram Water to equal liler Thisstep is followed by washing off the unhardened layers for about to 30seconds in water having a temperature of about 120 F. although the washcan vary from 70 F. to 140 F. The water is sprayed over the elementfacilitating easy removal which is finally accomplished by simplypeeling off the unhardened gelatin layer by moderate pressure along theelement. This demonstrates that the hardener remained only 4 in thelayers in which it was placed, failing to migrate into the unhardened ornonhardened layers, the removal of which was easily accomplished becauseof their relative softness.

Similar results are obtained when the hardeners described herein areemployed in photographic emulsions using a mixed vehicle or binder ofsynthetic polymer along with gelatin. For example, one such vehicle uses3 parts of polymer and 1 part of gelatin by weight wherein the polymeris a copolymer composed of 80 percent ethylacrylate and percent acrylicacid and is coated at 500l,000 mg. per square foot. In another vehiclethe copolymer consists of 90 percent butylacrylate and 10 percentacrylic acid in place of the 80/20 ethyl-acrylateacrylic acid copolymcr.

From the foregoing examples, it can be seen in part that the new classof low molecular weight hardeners of this invention possesses goodhardening properties in a low concentration when added to hardenablematerial such as polymeric compounds like gelatin or synthetic polymers,alone or in combination with each other. Further, these new hardenersexert their hardening effect rapidly without adverse afterhardening andwith substantially no adverse sensitometric effect. Because they arenonwandering and can selectively harden the various layers of hardenablematerials in which they are incorporated, they are particularly usefulin photographic elements and similar systems.

Although this invention has been described in considerable detail withparticular reference to certain preferred embodiments thereof,variations and modifications can be effected within the spirit and scopeof the invention as described hereinbefore and as defined in theappended claims.

There is claimed: 1 v

1. In a photographic element comprising a support, a silver halideemulsion and a hardenable colloid containing amine groups, which colloidis hardened, the improvement wherein said colloid is hardened by acompound having the structural formula wherein each R is hydrogen, or analiphatic or aromatic radical, and R and each R are hydrogen or loweralkyl.

2. In the element of claim 1, the Improvement wherein said silver halideemulsion comprises said colloid which is hardened by a compound havingthe structural formula of claim 1.

3. A silver halide containing emulsion comprising a hardenable colloidcontaining amino groups which colloid is hardened by a compound havingthe structural formula:

R3 0 O 0 R;

. v R s B H R wherein each R is hydrogen, or an aliphatic or aromaticradical and R and each R are hydrogen or lower alkyl.

4. The emulsion of claim 3 hardened by a compound having the structuralformula of said claim in which each R, R and each R are hydrogen.

2. In the element of claim 1, the improvement wherein said silver halideemulsion comprises said colloid which is hardened by a compound havingthe structural formula of claim
 1. 3. A silver halide containingemulsion comprising a hardenable colloid containing amino groups whichcolloid is hardened by a compound having the structural formula: whereineach R is hydrogen, or an aliphatic or aromatic radical and R2 and eachR3 are hydrogen or lower alkyl.
 4. The emulsion of claim 3 hardened by acompound having the structural formula of said claim in which each R, R2and each R3 are hydrogen.
 5. The emulsion of claim 3 hardened by acompound having the structural formula of said claim in which R2 ishydrogen, one R is hydrogen and the other methyl and each R3 ishydrogen.
 6. The emulsion of claim 3 hardened by a compound having thestructural formula of said claim in which the R2 is methyl and each Rand each R3 are hydrogen.